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TO ALL WHOM IT MAY CONCERN:

Be it known that I, Cynus HENRY MERRICK, of Pittsburg, in the county of Allegheny, and State of Pennsylvania, have invented a new and useful Improvement in Steam Engines; and I do hereby declare the following to be a full, clear, and exact description thereof, reference being bad to the accompanying drawings, making a part of this specification, in which Figure 1 is a top view of the valve-chests and cylinder, the cover of the chests, the valves, and valve-rods being removed so as to show the valve-seats and ports. i

I Figure 2 is a vertical cross-section of. the cylinder, valve-chests, valves, etc.

Figures 3 and 5 show a vertical section formed by planes passing longitudinally through the cylinder and balancing-valve in the line 3 .2, fig 2; and showing the positions of the balancing-valve at different points of the stroke; and

Figuresl and 6 are also sectional views formed by planes passing longitudinally through the cylinder and steam-valve in the line :v z, (fig. 2,) and also showing the steam-valve in the two positions it occupies at difi'erent points of the stroke.

Like letters of reference indicate like parts.

The design of my invention is to utilize more perfectly than has heretofore been done the force of steam, hot or compressed air, or other fluid motors, as applied to the production of rotary motion, by means of a cylinder, piston, crank, and otherappliances well known and in common use for such purposes.

The ofiice of the crank in the steam engine, it is well known, is totransmit the power of the steam, and convert the reciprocating motionof the piston into rotary or circular motion. It is also manifest that at two points in the stroke, commonly called the dead-points, the crank can transmit no power, from the fact that at these points it is acting in the line of stroke, and has no lever value. After passing the dcad-points its value commences, and increases but very slowly to at or near the end of the first quarter or third of the stroke, from which point it increases with great rapidity, so that the maximum value ofthe crank as a lever and as a transmitter of power is attained when at right angles to the line of stroke, or, in other words, at or near half stroke. For the same reasons the leverage of the crank, and consequently its value, dccreasewith equal rapidity from such maximum point, till at the other dead-point it entirely disappears. Hence it is evident that a material saving will be eflected, if, instead of applying the motive power to the piston at the beginning of the stroke, where it has no value, and continuing such application to the end of the stroke, where its value disappears, we concentrate the power on or apply it to the piston during that portion of the stroke where the position of the crank gives it its greatest value. In the ordinary construction of engine such concentration is partially attained by cutting off the steam before reaching the end of the stroke, though this is done for another reason, but it is only partially attained, since it still remains necessary to admit the motor to the cylinder at the commencement of each movement or stroke of the piston in order to avoid the vacuumand consequent back pressure which would be caused by deferring its admission.

In my invention I propose to obviate this difiiculty, and utilize the steam to the greatest possible extent by not admitting live steam into the cylinder of the engine during the first quarter or third of the stroke, using the steam so admitted till the last third or quarter of the stroke is reached, at which points the steam and exhaust-ports are both closed. The points of opening and closing the steam and exhaust-ports may be varied, so as to be at such distances from the ends of the stroke as may be found most advantageous. I thus usethe live steam only when the position of the crank enablesmc to use it most eil ectivcly. And to obviate the cliihculty of back or retarding pressure at the commencement and end of the stroke, I open a separate communication between the two ends of the cylinder for the purpose of permitting the exhaust steam in the cylinder to pass back of the piston-head, and thereby I secure for the piston-head a. perfect balance. The steam will pass freely through such communication from the front to the rear of the piston-head, and thus prevent the formation of a vacuum, obviate back pressure, and equalize the pressure exerted on opposite sides of the piston-head.

The nature of my invention, then, consistsin balancing the piston-head'of an engine while the crank is passing the dead-points, and for any desirable part of the stroke before and after, by the use of exhaust while-the crank is approaching to, passing, and receding from the dead-points or centres during any desirable portion of the stroke, substantially as and for the purposes above described.

3. So constructing and arranging the steam-valve and ports of it steam engine as to admit steam to the cylinder during the middle of each stroke, and for a, greater or less proportion of such stroke, in combination with one or more openings or communicating passages from end to end of the cylinder, fitted with :tvelve or valves, or otlier snita-ble device for permitting or preventing the flow of steam in order to balance the piston, substantially in the manner and for the purposes hereinbefore set forth.

I testimony whereof I, the said CYRUS HENRY MERRIGK, have hereunto set my hand in the presence of CYRUS HENRY MERRICK.

Witnesses:

A. S. NICHOLSON, G110. H. OnRIsrY. 

